I changed the margins on all my pages (and masters) because this looks better. But, now I have to change all the text frames on all 70 pages separately to fit those margins (it seems). Is there a way to change all of this at once?
To be clear:
1) I changed the top- and bottom margin, so the height of the text frame needs to change.
2) I increased the gutter, so I have to change this in the text frame options.
Best to set up your document with "Primary Text Frame" when starting, which will automatically change your document pages.
But if not, try this:
Reset your document margins as they were originally. Go to the Master page and choose the Page Tool (3 tools down in panel) and at top set "Liquid Page Rule" to "Guide Based." Adjust your margins (which are guides), then the master frame on the master page. All your document pages should update.